Existing sheeting comprises the two layers of plastic sheeting laminated together to form a so-called bubble plastic material. The bubble shapes are vacuum-formed in one sheet (which is the case of swimming pool covers is the bottom sheet) and this is then laminated to a substantially flat sheet, to form sealed bubbles between the two layers.
The bubbles normally have a circular cylindrical shape, but hexagonal, diamond-shaped and part-spherical bubbles are also known.
U.S. Pat. No. 4,869,939 discloses sheets of air encapsulating cellular material comprising an array of cells, adjacent ones of which are in flow communication with each other via intermediate passages.
JP 20032377842A discloses a sheet with air bubbles connected in groups by intermediate connection passages.